If you can start off with something that makes the audience laugh, it will become much easier.

I'd actually tell the rest of the class that you're scared shirtless so please excuse any stutterings or memory loss. That will pretty much resonate with everyone.

All eyes upon you? Probably for the first few seconds then other students will doze off or start thinking about their own presentations.

I hate teachers who make students do presentations. They are lazy barstewards who don't have to teach anything. Money for old ripe